A photovoltaic module is designed by electrically connecting a plurality of photovoltaic cells in series so that a predetermined output can be obtained.
In certain situations when the photovoltaic cells are not generating electricity (in situations when the sun light to the photovoltaic cells is obstructed), their resistivity increases and the electrical power that can be extracted decreases. Also, there is a possibility that heat will be generated due to the resistive loss and this may lead to heat damages and the like. Thus, diodes are electrically connected in parallel to the photovoltaic cells and when there is a failure in the photovoltaic cells, currents are bypassed through the diodes. This way, decrease in the extracted electrical power and damages to the photovoltaic cells are prevented. The diodes connected in this way are called bypass diodes.
Typically, molded type diodes are connected to the outer sides of the photovoltaic cells as bypass diodes. However, in the case of molded type diodes, it was necessary to install respective diodes one by one to the photovoltaic cells. This was a problem because of its low workability in attaching them. Also, since the diodes are disposed on the outer sides of the photovoltaic cells, the area not contributing to the electric generation increases and there was a problem that the electricity generation capacity per unit area decreases.
Patent Document 1 discloses protection diodes that are formed by laminating a metallic electrode, an amorphous silicon layer, and a metallic electrode in this order on a flexible thin film on a metallic electrode layer side of a thin film photovoltaic cell. Patent Document 1 further discloses that many protection diodes can be formed on a common insulating substrate and attached onto the photovoltaic element.